Scientists are convinced______ the positive effect of laughter______ physical and mental health

Your handwriting is really too bad to read; I can hardly _____ what exactly you are trying to say.

依次填入下面一段文字横线处的语句，衔接最恰当的一组是天鹅悠闲自在、无拘无束，它时而在水上遨游， ——它似乎是很喜欢接近人的，只要它觉得我们不会伤害它。①时而沿着水边， ②回到有人的地方，③时而到岸旁嬉戏， ④享受着与人相处的乐趣，⑤时而离开它的幽居， ⑥藏到灯芯草丛中，

Which car is _______, the yellow one or the red one —The red one, I think.

Look at the weeds and wildness now! — Hard to _______ that the scene was once so grand.[ ]